• 한국전문물리치료학회지
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• 제11권3호
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• pp.11-18
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• 2004

This study is aimed at investigating the influence of different quantitative knowledge of results on the measurement error during lumbar proprioceptive sensation training. Twenty-eight healthy adult men participated and subjects were randomly assigned into four different feedback groups(100% relative frequency with an angle feedback, 50% relative frequency with an angle feedback, 100% relative frequency with a length feedback, 50% relative frequency with a length feedback). An electrogoniometer was used to determine performance error in an angle, and the Schober test with measurement tape was used to determine performance error in a length. Each subject was asked to maintain an upright position with both eyes closed and both upper limbs stabilized on their pelvis. Lumbar vertebrae flexion was maintained at $30^{\circ}$ for three seconds. Different verbal knowledge of results was provided in four groups. After lumbar flexion was performed, knowledge of results was offered immediately. The resting period between the sessions per block was five seconds. Training consisted of 6 blocks, 10 sessions per one block, with a resting period of one minute. A resting period of five minutes was provided between 3 blocks and 4 blocks. A retention test was performed between 10 minutes and 24 hours later following the training block without providing knowledge of results. To determine the training effects, a two-way analysis of variance and a one-way analysis of variance were used with SPSS Ver. 10.0. A level of significance was set at .05. A significant block effect was shown for the acquisition phase (p<.05), and a significant feedback effect was shown in the immediate retention phase (p>.05). There was a significant feedback effect in the delayed retention phase (p<.05), and a significant block effect in the first acquisition phase and the last retention phase (p<.05). In conclusion, it is determined that a 50% relative frequency with a length feedback is the most efficient feedback among different feedback types.

• 한국수학교육학회지시리즈A:수학교육
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• 제57권1호
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• pp.55-74
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• 2018

The purpose of this study is first to examine the relative influence of each error source and to investigate the optimal measurement conditions to ensure satisfactory multiple reliability coefficients based on the teaching aptitude and personality test for pre-service teachers. Participants were 33 students enrolled in mathematics education in a graduate school of education located in the Seoul metropolitan area from 2013 to 2017. The main results were as follows. First, the estimated variance due to residual was highest, followed by nesting of items within domains, graduate students, interactions of graduate students with domains, and domains. Second, total 96 items, with 12 domains containing 8 items in each domain, with cut score of 598, and original 210 items, with 14 domains containing 15 items in each domain, with cut scores of 615 or 716 were optimal measurement conditions to reach acceptable reliability levels based on the joint consideration of dependability coefficients, cut score dependability coefficients, adjusted dependability coefficients, and standard errors of measurement. Third, larger deviations between the arithmetic mean and the cut score indicated higher reliability coefficients of the test results. Finally, this study suggests ways for practitioners to consider how to apply generalizability theory for criterion-referenced tests and how to develop future research based on limitations.

• 한국항해항만학회지
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• 제29권3호
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• pp.269-274
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• 2005

현재 국내에서 활발히 이루어지고 있는 GPS 정밀측지측량은 GPS 관측성과가 관측값의 통계적 검증없이 이루어지고 있단 문제점이 있다. 그리고 육지와 해상의 통합지리정보시스템구축을 위한 수치지형도와 수치해도의 통합투영의 필요성이 요구되고 있다. 본 연구를 통하여 GPS 망조정에 사용되는 3점의 기준선에 대한 기하학적인 강도에 따른 정밀도 분석과 분산계수의 변화에 따른 GPS 관측 값들의 정밀도 분석방법으로 GPS 관측값의 정밀도 향상을 위한 방법을 제시하였다. 또한, GPS 관측값의 정밀도를 향상시키는 방법과 수치지도와 전자해도의 통합투영으로 GPS 기준점을 이용한 수지지형도와 수치해도의 경계선 오차량을 비교 검토하여 수치지형도와 수치해도의 통합관리의 방향을 제시하였다. 그리고 이렇게 산출된 GPS 관측결과를 이용하여 EDM 측량결과를 산출하고 수치지형도와 수치해도를 이 정계값들로 맞추었을 때 전체적인 경계점 오차량을 비교 검토하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.275-281
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• 2004

현재 국내에서 활발히 이루어지고 있는 GPS 관측성과가 관측값의 통계적 검증없이 이루어지고 있는 문제점이 있다. 그리고 육지와 해상의 통합지리정보시스템구축을 위한 수치지형도와 수치해도의 통합투영의 필요성이 요구되고 있다. 본 연구를 통하여 GPS 망조정에 사용되는 3점의 기준점에 대한 기하학적인 강도에 따른 정밀도 분석과 분산계수의 변화에 따른 GPS 관측값들의 정밀도 분석방법으로 GPS 관측값의 정밀도 행상을 위한 방법을 제시하였다. 또한, GPS 관측값의 정밀도를 향상시키는 방법과 수치지도와 전자해도의 통합투영으로 GPS 기준점을 이용한 수치지형도와 수치해도의 경계선 오차량을 비교검토하여 수치지형도와 수치해도의 통합관리의 방향을 제시하였다. 그리고 이렇게 산출된 GPS 관측결과를 이용하여 EDM 측량결과를 산출하고 수치지형도와 수치해도를 이 경계값들로 맞추었을 때 전체적인 경계점이 오차량을 비교 검토하였다.

• Journal of Korean Neurosurgical Society
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• 제39권4호
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• pp.256-259
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• 2006

Objective : Having a reliable and reproducible measurement technique to measure the sagittal contour in vertebral fractures is paramount to clinical decision making. This study is designed to determine the most reliable measurement technique in osteoporotic vertebral compression fracture. Methods : Fifteen lateral radiographs of thoracic and lumbar fractures were selected and measured on two separate occasions by three spine surgeons using six different measurement techniques [Centroid, Harrison Posterior Tangent Methods and 4 different types of modified Cobb method]. The radiograph quality was assessed and the center beam location was determined. Statistical analysis including ANOVA for repeated measures was carried out using the SAS software [v 8.0]. Results : The inter and intraobserver variance of the Cobb method 4 and Harrison posterior tangent method were significantly lower than the other four methods. The intraobserver correlation coefficients were the most consistent using the Cobb method 4 [0.982]. which was followed by the Harrison posterior tangent [0.953] and Cobb methods 1 [0.874]. The intraobserver agreement [% of repeated measures within 5 degrees of the original measurement] ranged from 42% to 98% for each technique for all three observers, with the Cobb method 4 showing the best agreement [97.8%] followed by the Harrison posterior tangent method [937%]. Conclusion : The Cobb method-4 and Harrison posterior tangent methods, when applied to measuring the kyphosis, are reliable and have a similar small error range. The Cobb method 4 shows the best overall reliability. However, the centroid method and Cobb method using a fractured endplate do not produce an accurate result due to inter and intraobserver differences in determining the baseline.

• 대한기계학회논문집
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• 제12권4호
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• pp.694-704
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• 1988

본 연구에서는 현장에서 흔히 수행되는 가공 후(post-process) 측정만을 이용 한 단일절삭(single-pass)으로써 공작물이 원하는 일정한 직경을 유지할 수 있다는 것 을 실험을 통해 검증해 보이고자 한다. 이와 같은 방식은 이미 보오링 작업 중 보오 링바의 노출 길이 변화에 따른 가공면의 내경 오차를 없애주기 위한 방법으로써 제시 된 바 있다. 즉 반복 최소 자승법(recursive least squares)으로 미리 가정된 절삭 조건과 공작물 처짐 사이의 관계식과 관련된 계수를 가공 후에 가공 공작물의 표면 측 정으로 매 번보정(update)시켜 줌으로써 일정 직경을 얻기위한 절삭조건을 결정하고자 한다.

• 대한전기학회논문지:전력기술부문A
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• 제48권8호
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• pp.996-1003
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• 1999

This paper propose a position-speed controller with an estimator which can estimate states and disturbance. The overall control system consists of two parts: the position-speed controller and an estimator. The Kalman filter applied as state-feedback controller is an optimal state estimator applied to a dynamic system that involves random perturbations and gives a linear, unbiased and minimum error variance recursive algorithm to optimally estimate the unknown state. Therefore, we consider the error problem about the servo system modeling and the measurement noise as a stochastic system and implement a optimal state observer, and enhance the estimate performance of position and speed using that. Using two-degree-of freedom(TDOF) conception, we design the command input response and the closed loop characteristics independently. The servo system is to improve the closed loop characteristics without affecting the command imput response. The characteristics of the closed loop system is improved by suppressing disturbance torque effectively with the disturbance observer using a inverse-transfer matrix. Therefore, the performance of overall position-speed controller is enhanced. Finally, the performance of the proposed controller is exemplified by some simulations and by applying the real servo system.

• 대한산업공학회지
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• 제34권1호
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• pp.23-31
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• 2008

This paper presents accelerated degradation test plans considering adoption of tightened critical values. Under arandom coefficient degradation rate and log-linear acceleration models, the asymptotic variance of an estimatorfor a lifetime quantile at the use condition as the optimization criterion is derived where the degradation ratefollows a lognormal and Reciprocal Weibull distributions, respectively and then the low stress level andproportions ofunits allocated to each stress level are determined. We also show that the developed test plans canbe applied to the multiplicative model with measurement error.

• ETRI Journal
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• 제34권5호
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• pp.684-689
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• 2012

A mode-singular-value-decomposition (SVD) maximum likelihood (ML) estimation procedure is proposed for the source localization problem under an additive measurement error model. In a practical situation, the noise variance is usually unknown. In this paper, we propose an algorithm that does not require the noise covariance matrix as a priori knowledge. In the proposed method, the weight is derived by the inverse of the noise magnitude square in the ML criterion. The performance of the proposed method outperforms that of the existing methods and approximates the Taylor-series ML and Cram$\acute{e}$r-Rao lower bound.

• 제어로봇시스템학회논문지
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• 제17권12호
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• pp.1183-1187
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• 2011

In this paper, an optimal FIR (Finite-Impulse-Response) filter is proposed for discrete time-varying state-space models. The proposed filter estimates the current state using measured output samples on the recent time horizon so that the variance of the estimation error is minimized. It is designed to be linear, unbiased, with an FIR structure, and is independent of any state information. Due to its FIR structure, the proposed filter is believed to be robust for modeling uncertainty or numerical errors than other IIR filters, such as the Kalman filter. For a general system with system and measurement noise, the proposed filter is derived without any artificial assumptions such as the nonsingular assumption of the system matrix A and any infinite covariance of the initial state. A numerical example show that the proposed FIR filter has better performance than the Kalman filter based on the IIR (Infinite- Impulse-Response) structure when modeling uncertainties exist.